Crutch



I 2,736,330 1956 A. wooD Feb. 28, CRUTCH Filed May 18, 1953 //v A. wooo,0R JNVENToR.

ArroR/vfn i United States Patent C) CRUTCH Lorin A. Wood, Los Angeles,Calif.

Application May 18, 1953, Serial No. 355,520

7 Claims. (Cl. 13S- 49) This invention relates to crutches used forwalking aids by disabled persons and is directed to an eflcient crutchconstruction that combines adjustability with structural simplicity.

Simplicity is achieved, in large part, by using a single columnarsupport member in the form of a tubular shaft having an under-arm restmember at its upper end, and having a handgrip member extendinglaterally from an intermediate portion of the single support shaft. Atiirst thought, it would seem that a thoroughly satis factory crutch ofthis character could consist simply of a straight shaft with a restmember positioned symmetrically on the upper end thereof and with thehandgripV member extending perpendicularly from the straight shaft. Inactual use, however, such a crutch is found to be awkward,uncomfortable, and noticeably fatiguing. The handgrip is an especiallydistracting source of discomfort since it does not handle in a naturalmanner, and changing its height on the shaft or rotating it about theshaft to various trial positions does not eliminate the discomfort.

The invention solves the difficulty of awkwardness and discomfort bypositioning the under-arm rest member in an off-center position on theupper end of the shaft with an intermediate portion of the handgrippositioned to be intersected by a straight line extending from thecenter of the upper rest member to the bottom end of the shaft. Such astraight line may be termed the support axis of the crutch.

The intermediate portion of the handgrip that is on this support axis isthe portion on which the heel of the users hand rests to transmit weightto the crutch. Thus, three support lines are placed in a straight line,namely: the upper support point at the center of application of weightto the under-arm rest member; the intermediate support point whereweight is transmitted to the handgrip; and the bottom support pointwhere the lower end of the crutch transmits the total weight to thefloor or ground. With such alignment of the support points, andespecially with the handgrip extending substantially perpendicular tothe support axis, there is a desirable naturalness in the manner inwhich the crutch responds to manual manipulation there being notroublesome tendency for the crutch to twist in response to the weightapplied to the handgrip.

In practice, it has been found that the desired result may be attainedwith the major portion of the shaft substantially straight, with theaxis of this major portion of the shaft at an angle of approximately 3degrees from the support axis and with the handgrip substantially normalto the support axis, i. e., inclined downward about 3% from 'a positionperpendicular to the axis of the straight portion of the shaft. Withthese angular relations, the central or intermediate portion of theshaft is oset from the support axis and, of course, the upper restmember is in offset position relative to .the axis of the intermediateand lower portions of the shaft. The whole shaft may be straight withthe upper ICC rest mounted thereon in such manner as to extend to oneside thereof or the upper end of the shaft may be bent or curved to holdthe upper rest member in the desired offset position.

With reference to adjustability, two adjustments are required, namely,adjustment in overall length and adjustment in the elevation of thehandgrip on the shaft. ln the preferred practice of the invention bothkinds of adjustment are achieved by means including adjustment screwsthat are concealed and yet readily accessible. Thus the only toolrequired to make a change in adjustment is a screw driver.

The various features and advantages of the inventio will be apparent inthe following detailed description considered with the accompanyingdrawings:

In the drawings, which are to be regarded as merely illustrative:

Figure 1 is a side elevation of a selected embodiment of the invention;

Figure 2 is a section taken on the broken line 2-2 of Figure l;

Figure 3 is a section taken along the line 3-3 of Figure l;

Figure 4 is a fragmentary View partly in section and partly in sideelevation showing the construction at the juncture between the handgripand the shaft;

Figure 5 is a sectional view of the bottom end of the crutch; and

Figure 6 is a side elevation of a second embodiment of the invention.

The principal parts of the first form of the invention shown in Figuresl and 5 include: a single support shaft 10; a rest member 11 on theupper end of the shaft for positioning under the arm crotch of the user;a lateral handgrip 12 positioned at an intermediate point on the shaft;and the usual rubber member 13 that forms a cushioning tip at the lowerend of the crutch for non-slipping contact with a support surface.

The rest member 11 is shaped with an upper arcuate support surface 17 toreceive the under-arm weight of the user with the center of the weightor downwardly applied pressure at the point indicated by the arrow 18.The handgrip 12 also bears a portion of the users weight which isapplied by the heel of the users hand in the region of the root of thethumb, the center of this application of downward pressure on thehandgrip being indicated by the second arrow 19. In accord with theinvention, these two centers of pressure application 18 and 19 are on astraight-line support axis 2t? which is indicated by the dotted line inFigure 1 and which extends to the center of the bottom end of thecrutch.

Since the pressure center 19 on the handgrip 12 is necessarily spacedaway from the juncture of the handgrip with the shaft 10, the shaft 10in the region of the handgrip is correspondingly oiset from the supportaxis 20. In this particular embodiment of the invention, the majorportion of the shaft 10 extending upward from the lower end of the shaftto a point above the handgrip 12 is substantially straight and therequired oifset of the shaft from the pressure point 19 on the handle 12is achieved by inclining this major straight portion of the shaft awayfrom the support axis 2t) by an angle of approximately 3 degrees.Preferably the bottom face 21 of the rubber member 13 is correspondinglyinclined by approximately 3 degrees from the axis 22 of the shaft tomake the bottom face substantially perpendicular to the support axis2l).

The upper rest member 11 may be of any suitable construction and may bemounted on the upper end of the shaft 10 in any suitable manner thatoffsets the upper pressure point 18 from the axis of the major portionof the shaft. In this first form of the invention, for example, theupper end of the shaft is curved across the support axis Ztl asindicated in Figure 1 for connection to the underside of the rest member11.

Preferably, the rest member 11 is a one-piece member of wood or asuitable plastic and is formedv with a groove o-n its underside toreceive the curved upper end of the shaft 1t). As indicated in Figure l,the rest member 11 may be attached to the shaft 10 by suitable screws26. it is advantageous to provide threaded tubular inserts (not shown)in the rest member for engagement by the screws. A further feature ofthe preferred practices of the invention is the formation of the restmember 11 with a central aperture 28 which not only serves to reduce theweight of the crutch and to improve the appearance of the crutch, butalso serves as means to permit the crutch to be hung on a hook or nailwhen not in use.

The mounting of the rest member 11 on a curved end portion of the shaft1i), in the manner described, has certain structural advantages. Theweight imposed on the shaft 16 by the rest member is distributed over arelatively extensive surface o-f the shaft so that concentration ofstresses is avoided. It is further apparent that only a minor componentof the applied vertically 'l downward pressure is directed across thescrews 26 perpendicularly thereof to stress the screws in shear.

The handgrip 12 may be mounted on the intermediate portion of the shaft1li in any suitable manner, but preferably in a manner permittingadjustment of the elevation of the handgrip. As best shown in Figure 3,the handgrip 12 may comprise a metal tube 3@ and a collar 31 integraltherewith for embracing the shaft lit) in a sliding manner. The interiorof this member provides a passage longitudinally of the handgrip havingthree parts, namely: a smooth inner bore 32 to slidingly house aclamping plug 33; an intermediate threaded portion 35 for a screw 36;and an outer smooth bore 37 of a diameter to admit the screw 36.Preferably a handle sleeve 38 of rubber-like material embraces the metaltube 30 to provide a yielding grip for the user.

In the described handgrip construction, the clamping plug 33 is adaptedfor pressure contact with the periphery of the shaft 10 and for thatpurpose the inner end of the clamping plug may be of forkedconfiguration, being formed with converging pressure faces du. lt isapparent that the screw 36 may be tightened to force the clamping plug33 into contact with the shaft 10 with sufficient pressure to immobilizethe handgrip 12 on the shaft, and that the screw 36 may be loosened whendesired to permit the handgrip to be adjusted upwardly or downwardly onthe shaft.

The feature of adjustability in length of the crutch may be provided invarious ways in various practices of the invention. As shown in Figure5, for example, adjustability may be achieved by using a supplementaltube 45 as an interchangeable extension at the lower end of the mainshaft tube l0. in the present construction, the suppiemental tube 4S ismounted coaxially on the end of the main tube 10 by means of a tubularcore 48 that has a circumferential end flange t9 to abut thesupplemental tube 45 and is adapted for insertion through thesupplemental tube into the main tube. The inner or upper end of thetubular core 48 is radially expansile for releasable engagement with themain tube 1t) and for this purpose is formed with a plurality ofexpansion fingers S0 at its inner end. Mounted inside the tubular core4S is a suitable screw Si. The expansion fingers Si) have convergentinner faces 52 in the path of the screw 51, so that tightening the screwexpands the fingers by wedging action into effective pressure engagementwith the surrounding wall of the main tube 10. It is contemplated that aseries of supplemental tubes 45 progressively varied in length will beavailable to be mounted interchangeably on the bottom end of 4 the maintube it) for the purpose of changing the effective length of the crutch.

The utility of the crutch and the manner in which it may be adjusted tomeet the needs of individual users may be readily understood from theforegoing description. rihe screw S6 inside the handgrip 12 is concealedbut nevertheless is conveniently accessible for rotation by an ordinaryscrew driver, so that the screw may be loosened for adjustment of theheight of the grip member without requiring any special tools andwithout requiring any special skill. The screw 51 at the bottom end ofthe crutch is also concealedV but `at the same time readily accessiblefor rotation by a screw driver so that the tubular core 48 may bewithdrawn from the lower end of the main tube 16 to permit thereplacement of the supplemental tube by a second supplemental tube ofdifferent length thereby to vary the effective length of the crutch.

The second embodiment of the invention shown in Figure 6 is largelyidentical with the first described embodiment of the invention, asindicated by the use of corresponding numerals to designatecorresponding parts. ln this particular construction, the tubular shaft10a is substantially straight throughout its length, beingA .inclinedapproximately 3 degrees from the support axis 20 as` heretoforedescribed. The rest member 55 on the upper end of the shaft 10a may beof `any suitable construction to place the pressure point 18 or centerof weight application in the offset relation with respect to the axisVof shaft 10a to conform to the support axis 20.

ln the illustrated construction, the rest member 55, which is formedwith a triangular aperture 56, isprovided with a cylindrical socket 57to receive the upper end of the tubular shaft 10a. Suitable cross pinsor screws 60 in the body of the rest member 55 may extend throughcorresponding apertures in the tubular shaft 10a for the purpose ofeffectively interlocking the rest member 55 with the shaft.

ln this embodiment of the invention the hand grip is mounted on theintermediate portion of the shaft 10a in exactly the same manner as isthe hand grip mounted in the earlier described embodiment of theinvention. In this form of the hand grip the rubber sleeve is moldedwith a laterally extending protuberanceA 38a which actsk to preventmovement of the hand. longitudinally of the hand grip in a directionaway from the tubular shaft forming the body of the crutch. This handgrip formation is of particular importance for patients who do not havefull control of their hands and who are not 'able to tightly clasp thehand grip during the use of the crutch.

Although the new preferred embodiments of the present invention havebeen shown and described herein, it .is to be understood that theinvention is not to be limited thereto, for it is susceptible to changesin form and detail within the scope of the appended claims.

l claim:

l. A crutch comprising: a single support shaft, an under-arm rest membermounted on the upper end of the shaft; and a handgrip mounted on saidshaft at an intermediate point thereof and extending laterallytherefrom, the upper end portion of said shaft being offset to extendfrom said rest member in a direction Iaway. from a straightline supportaxis extending from the center of' weight application on said restmember to the bottom end of the shaft, the remaining major portion ofsaid shaft below said offset end portion being substantially straightwith said support axis intercepting the intermediate portion of saidhandgrip where weight is imposed by the users hand.

2. A crutch as set forth in claim l in which said rest member is aone-piece member having a transverse aperture to lighten the crutch andto permit the crutch to be hung up when not in use.

3. A crutch as set forth in claim l in which the upper end of said shaftabove the level of the lowermost part of said rest member curveslaterally across said support axis and in which said rest member isattached to the upper side of said curved end. l

4. A crutch as set forth in claim 1 in which said center of Weightapplication on said rest member is offset from the axis of the straightportion of the shaft in the plane of said handgrp.

5. A crutch as set forth in claim 1 in which the major straight portionof the shaft is at an angle of approximately 3 degrees from said supportaxis.

6. A crutch as set forth in claim 5 in which the axis of said handgrp-is substantially perpendicular to said support axis.

7. A crutch as set forth in claim 6 in which said handgrip is adjustablealong the straight portion of the shaft.

References Cited inthe le of this patent UNITED STATES PATENTS CalentineApr. 14, 1903 Seyferye Dec. 26, 1944 Wheeler Nov. 13, 1945 Brickson Oct.1, 1946 Neptune Sept. 18, 1951 Henderson et al. June 23, 1953 FOREIGNPATENTS Norway Sept. 16, 1940

